There are numerous devices for delivering medicament on the market where the medicament is arranged in a container, such as a syringe, a cartridge or the like, and wherein the medicament is ejected through a delivery member, such as a needle or a nozzle, by driving a movable stopper inside the container.
The stopper is exposed to pressure, i.e. pushed into the compartment by a plunger rod. Actuation of the plunger rod could be done manually, as in the case of standard handheld syringes, or by pressure means such as springs. The latter is common in automatic or semi-automatic injectors. An example of a manual delivery device is the so called pen-injector.
Different dose setting mechanisms have been developed for pen injectors to allow control of the dose to be delivered. Different factors determine the required amount of medicament, such as the severity of the ailment, the required effect, the body mass of the user, etc. One important aspect of dose setting is to prevent the user from over-dosing the drug. A solution to the problem is presented in U.S. Pat. No. 8,545,456, wherein a pen injector is disclosed, having a dosage setting member that is rotated along a thread, relative to a casing. A rotational block is provided, which rotational block comprises a first and a second rotational stopper, such that when the dosage member has been rotated a certain distance, i.e. to an end position, the first and the second rotational stoppers abut against each other to prevent further rotation in that direction. The range of rotation allowed is set during design of the device and determines the maximum dose that may be set.
However, there are alternative solutions for providing a maximum dose stop, as will be described herein.